Thanks gents. I had looked at Kendazut's dovetails but noticed that his CG5 one had holes for the 2 rear screws and 1 for the front screw...not ideal. In general there must be many OTAs out there with this similar dovetail fitment (read not much holding them to the dovetail).
I see that the wider dovetails (re:Losmandy) allow fitting of radius blocks which I see as a good thing but alas the wider dovetail won't fit on a GC5.
I like the idea of radius blocks and would be comfortable drilling and tapping knowing there was better support on the OTA. If only the wider dovetail would fit the CG5!
Decisions Decisions!
Thanks for your input guys it's given me some ideas
edit:
Ken does have adaptors but they are a bit pricey.
http://www.kendauzat.net/other/1021051b.jpg
Then you need a Lomsandy dovetail on top of that.